don't enable stats counters when not compiled with debug
always enable array fusion

Since the type of the fused result changes, we can't just toggle it with a configuration flag. May need to reconsider this…
re-export fusion & substitution stuff from trafo, hide modules
don't put the Extensions list in the .cabal file

Placing individual LANGUAGE pragmas in each file ensures the project loads with ghci, and avoids extension clashes (e.g. OverloadedStrings in a file not expecting it)
polish slightly the delayed array representation used by the interpreter